The Ganga is flowing over the danger level in Bihar and is likely to flood large parts of capital Patna by Wednesday afternoon.
Some low lying areas of Patna were inundated on Tuesday night.
People have begun evacuating low-lying areas following warnings of floods.
Patna district administration officials confirmed that flood waters have entered Durja, Sadaqat Ashram and Digha areas of Patna.
According to Central Water Commission officials the Ganga is flowing above the danger level at several places like Dighaghat and Gandhighat.
Patna District Magistrate Deepak Prasad, however, said the situation is under control.
He said a team of district administration officials along with officials of the irrigation and flood control department have taken stock of the situation. "We have taken all precautionary measures," he said.